What communications equipment do you need for IFR operations?
In uncontrolled airspace, none is required by regulation.

What you need is up to your own judgment.

For operations under IFR in controlled airspace, two regulations
relate directly to the minimum communications equipment:

a. (FAR 91.33 {§ 91.33 recodified to § 91.205})
Your aircraft must be equipped with a two-way radio communications system
appropriate to the ground facilities being used.
b. (FAR 91.125 {§ 91.125 recodified to § 91.183})
The pilot in command shall have a continuous listening watch maintained
on the appropriate frequency and shall report by radio as required.

Information on making radio reports and on the functions and services
of Air Traffic Control agencies are considered in Chapter XI.

Communications with these controlling units are normally conducted
on VHF frequencies between 118.000 and 136.000 MHz. Flight Service Stations,
while not exercising direct control over IFR aircraft, are ground facilities
available and used for radio communications. They play an important role
in the total ATC system (see pages 193 through 195 for details).
Automatic Terminal Information Service (ATIS) is provided at
certain high activity terminal areas. Recorded information on weather,
altimeter settings, instrument approaches and runways in use, tower frequencies
etc., is broadcast continuously on a specific VHF frequency.

The frequencies with which you should be familiar are listed below.
The ILS and VOR frequencies listed may be used as receiving frequencies
for communications as well as for navigation.

Radio communications requirements have increased with the growth
of aviation. Implementation of 25 kHz spacing in 1977 now provides 720
VHF channels (118.000 - 136.000) for air/ground communications. For training,
however, you need only a transmitter and receiver suitable for communications
with the ground facilities in your training area. Any lightweight equipment
which provides the minimum standard frequencies included in the table above,
may be sufficient for training but may be inadequate for the instrument
rated pilot.

Communications equipment of more recent design reflects the concern
of
manufacturers for the operational needs of the instrument pilot. Under
the best conditions, a pilot flying on instruments must think, decide,
and move quickly. Equipment design that contributes to indecision, uncertainty
or fatigue creates unnecessary problems when the pilot is flying by reference
to instruments.

"One and One-half" Systems

Figure 9-1 illustrates a dual-purpose radio typical of the "one
and one-half" systems. These systems incorporate communications and navigation
radios in a single compact unit. This is a welcome change from the older
installations that required an extensive cockpit search to locate switches,
selectors, and associated indicators and too much time to tune and operate.
The "one and one-half" radio enables you to communicate with the necessary
ground facilities on the transceiver (combined transmitter/receiver) while
simultaneously tuned on the separate "one-half" of the set to a VOR station.
This radio has controls that are easily identifiable and crystal-tuned
frequencies that can be selected with only a glance or two for tuning.

Figure 9-1. "One and one-half" system.

Operation of the communications sections of these radios is simple.
The volume switch on the left is the ON/OFF switch for both COMM and NAV
sections. The squelch knob is rotated to reduce background noise. While
the set is warming up, set the knob fully clockwise; then turn the control
counterclockwise to increase the squelch until the background noise is
cut out. Further increase of the squelch setting will decrease receiver
sensitivity. If you are tuning in a weak signal, decrease the squelch.
Otherwise, once the control is established at a comfortable level, no further
adjustment is necessary except to make an occasional check of receiver
sensitivity. Transmit/receive frequencies are selected by rotation of the
inner and outer knobs on the COMM side of the set.

The "one and one-half" system described has the following communication/navigation
frequency coverage:

Communications
Transmit/receive 360 channels (118.00
- 135.95 MHz)

Navigation
All VOR and localizer frequencies (108.00
- 117.95 MHz)

Expanded NAV/COMM Systems

The advantages of the "one and one-half" system can be expanded
with installation of additional radios and centralized control units for
rapid selection of receivers and transmitters. The "building block" concept,
from which most light aircraft radio design evolves, provides for progressive
expansion of your equipment as your training and operational needs increase.
For example, if you depart under IFR from an uncontrolled airport and proceed
via Victor airway to another uncontrolled airport, your communication/navigation
needs may be as little as one VOR frequency and one transmitting frequency
for communication with FSS.

When you progress to all-weather IFR flying in and out of unfamiliar
terminal areas, your workload can be excessive unless you have sufficient
standby equipment for frequent changes of communications channels. Figure
9-2 shows how communications equipment can be grouped for quick reference
and operation with minimum distraction from the problem of aircraft control.

Figure 9-2. Full navigation-communications panel.

Radiotelephone Procedure

From the time you contact ground control for taxi instructions
the effectiveness of your coordination with Air Traffic Control will depend
upon your competence in communications and your knowledge of traffic procedures
under Instrument Flight Rules. Many students have no serious difficulty
in learning basic aircraft control and radio navigation, but stumble through
even the simplest radio communications. During the initial phase of training
in Air Traffic Control procedures and radiotelephone techniques, some students
experience difficulty.

Why should talking and listening to a controller pose any problems?
The average person takes speaking and listening habits for granted and
has had no occasion to develop the specialized skills associated with radio
communications. Studies of listening comprehension show that most people
listen with low efficiency even when consciously attempting to remember
what they hear. Poor listeners are easily distracted. From habit, they
tolerate conditions unfavorable to concentration. Their minds wander when
they hear anything unexpected or difficult to understand. They are inclined
to be more concerned with what they are about to say than what they should
be listening to. When in confusing situations, they are more easily aroused
emotionally, and may have trouble comprehending what they hear.

These deficiencies are intensified for the pilot in a busy air
traffic environment. In addition to attending to cockpit duties demanding
rapid division of attention, quick judgment, concentration, and careful
planning, you the pilot must be continuously alert to communications from
Air Traffic Control. You should be prepared to listen and to transmit in
the brief and unmistakably clear terms vital to orderly control.

You attain proficiency in radiotelephone technique just as you
do in developing any other skill. You should first recognize that radio
communications under Instrument Flight Rules, though not difficult, require
speaking and listening habits different from those you have been accustomed
to. Skill in transmitting and listening will come rapidly once you have
studied and practiced the basic terminology.

FAA controllers are intensively trained to speak clearly and concisely
in an abbreviated terminology. They use standard words and phrases to save
time, reduce radio congestion, and lessen the changes of misunderstanding
and confusion. However, the most competent controllers won't "get through"
to you under the best conditions unless you are ready to listen and understand.
Communication is a two-way effort, and the controllers expect
you to work toward the same level of competency that they strive to achieve.
Tape recordings comparing transmissions by professional pilots and inexperienced
or inadequately trained general aviation pilots illustrate the need for
effective radiotelephone technique. In a typical instance, an airline pilot
made a position report in 5 seconds; whereas a private pilot reporting
the same fix took 4 minutes to transmit essentially the same information.
The difference lay not in equipment and flight experience, but in communication
technique. The novice forgot to tune the radio properly before transmitting,
interrupted other transmissions, repeated unnecessary data, forgot other
essential information, requested instructions repeatedly, and created the
general impression of cockpit disorganization. The novice who is embarrassed
and concerned about inexperience should remember that every pilot had to
make a beginning and was not expected to first communicate like a veteran
airline pilot. But the private pilot who learns and practices standardized
words and phrases until they become part of the normal radio vocabulary
will be able to communicate effectively even under severe reception conditions.

Phonetic Alphabet

It is often necessary in transmitting to identify certain letters
and/or groups of letters, or to spell out difficult words, since certain
sounds have low intelligibility when mixed with a background of other noises.
The standard phonetic alphabet (Fig. 9-3) identifies each letter of the
alphabet with a word that is easily understood. These words are pronounced
to make the message clear when individual letters ar transmitted, and are
used to spell out words that are hard to understand on the air.

Numbers are usually of extreme importance in radio messages and
are difficult to hear among other noises. The standard pronunciations in
Figure 9-3 have been adopted because they have been found most intelligible.
a. Normally, numbers are transmitted by speaking each number
separately. For example, 3284 is spoken as "tree too ait fo-wer."
b. There are certain exceptions to the above rule. Figures indicating
hundreds and thousands in round numbers, up to and including 9,000 are
spoken in hundreds or thousands as appropriate. 500 is spoken as "fife
hundred"; 1,200 as "wun thousand too hundred." Beginning with 10,000, the
individual digits in thousands of feet are spoken. For 13,000, say "wun
tree thousand", for 14,500, say "wun-fo-wer thousand fife hundred."
c. Aircraft identification numbers are spoken as individual
digits/letters. 1234Q is spoken as "wun too tree fo-wer Keh-beck."
d. Time is stated in four digits according to the 24-hour clock.
The first two digits indicate the hour; the last two, minutes after the
hour (Fig. 9-4), as in "wun niner too zero"; "zero niner fo-wer fife."
e. Field elevations are transmitted with each number spoken
separately, as in Figure 9-4.

------------------------------------------------------------------------
Word or phrase
Meanings
------------------------------------------------------------------------
Acknowledge ............ Let me know that you have
received and
understand this message.
Affirmative ............ Yes.
Correction ............. An error has been made
in this transmission.
The correct version is....................
Go ahead ............... Proceed with your message.
How do you hear me? .... Self explanatory.
I say again ............ Self explanatory.
Negative ............... That is not correct.
Out .................... This conversation is ended
and no response is
expected.
Over ................... My transmission is ended
and I expect a
response from you.
Read back .............. Repeat all of this message
back to me exactly
as received after I have given "over."
Roger .................. I have received all of
your last transmission.
(To acknowledge receipt; shall not be used
for any other purpose.)
Say again .............. Self explanatory.
Speak slower ........... Self explanatory.
Stand by ............... If used by itself it means,
I must pause for
a few seconds. If the pause is longer than a
few seconds or if "standby" is used to prevent
another station from transmitting, it must be
followed by the word "out."
That is correct ........ Self explanatory.
Verify ................. Check with the originator.
Words twice ............ As a request - Communication
is difficult:
Please say every word twice.
------------------------------------------------------------------------
Figure 9-5. Radiotelephone words and phrases.

Procedural Words and Phrases

The words and phrases in Figure 9-5 should be studied and practiced
until they are readily and easily used and clearly enunciated. To pilots
and controllers, their meanings are very specific. Careless or incorrect
use can cause both delay and confusion.

Voice Control

Students inexperienced in the use of the microphone are usually
surprised at the quality of their own transmissions when they are taped
and played back. Words quite clear when spoken directly to another person
can be almost unintelligible over the radio. Effective radiotelephone technique
sounds self-conscious and unnatural when you practice it, both because
the terminology is new and because you are habitually more concerned with
what you are saying than in how it sounds. Maximum readable radiotelephone
transmissions depend on the following factors:

1. Volume. Clarity increases with volume up to a level just short
of shouting. Speaking loudly, without extreme effort or noticeably straining
the voice, results in maximum intelligibility. To be understood, the spoken
sound must be louder at the face of the microphone than the surrounding
noises. Open the mouth so the tone will carry to the microphone. A higher-pitched
tone is easier to hear than a lower one. A distinct and easily readable
side tone in your earphones or speaker is a reliable index of correct volume.
2. Tempo. Effective rate of speech varies with the speaker,
the nature of the message, and conditions of transmission and reception.
Note the following suggestions for improving your rate of transmission:
a. Talk slowly enough so that each word and phrase is
spoken distinctly, particularly key words and phrases.
b. Talk slowly enough so the listener will have time,
not only to hear, but to absorb the meaning.
3. Pronunciation and Phrasing. As you notice the differences
in the transmission of various pilots and controllers, you can readily
identify those with exceptional skill. They sound natural and unhurried.
The words are grouped for easy readability. they pronounce every word clearly
and distinctly without apparent effort, without unnecessary words, and
without "uh's" and "ah's". They create the impression of competence that
any expert conveys after enough study and practice.

Practice

Many excellent audio training aids are available for practicing
radiotelephone procedures. With tapes or records, a microphone, and writing
materials, you can develop communications skills under excellent simulated
conditions. Practice until you can transmit concisely, hear accurately,
and listen critically. Hearing is largely a matter of having an adequate
receiver and knowing how to tune it. Critical listening is a more complicated
skill. You are ready to listen to a controller when you are thoroughly
familiar with your communications equipment and are ready to copy the transmissions,
evaluate what is said, and if necessary read it back without neglecting
other cockpit duties that may demand your attention. Study of Air Traffic
Control procedures under Instrument Flight Rules will enable you to "keep
ahead" of communications - just as you keep ahead of your basic flying
and navigation - by knowing what is ahead of you and attending to details
in the proper sequence at the appropriate time.

Reminders on Use of Equipment

1. Maintain a "readiness" to communicate. With your flight log
handy, charts in order, and other necessary materials readily available,
you can eliminate fumbling and confusion. You cannot organize an intelligible
message, or listen to one, in a disorganized cockpit.
2. Know your radiotelephone equipment and practice tuning it.
Check the knobs, switches and selectors before you transmit. Monitor the
frequency you are using before transmitting. If you hear nothing on a normally
busy terminal frequency, for example, check your volume control; you may
be interrupting another transmission.
3. Never subordinate aircraft control to communications. Don't
turn your aircraft loose in your haste to transmit.
4. Learn to take notes as you listen. Make written notes of times,
altitudes, and other information as you hear it. You have enough to think
about in planning ahead without having to waste time thinking back.